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EchelonVPS
operations · 2024-11-19

Port 25, and why deliverability is a policy problem

Self-hosted mail fails on reputation, not software. What we do about it, and what you have to do yourself.

Updated
2024-11-19
Operations
5 min
All
6 / 10

Port 25 is closed on new instances. Customers occasionally read that as hostility toward self-hosted mail, which is backwards — it is the reason self-hosted mail works here at all.

The mechanics of a burned range

One compromised instance sending spam for six hours can get a /24 listed at Spamhaus. Once listed, every customer in that range has a deliverability problem, and delisting takes days. Opening port 25 by default converts a single customer's bad night into everyone's week.

What we actually do

  • 01Port 25 opens on request, usually within the hour. Tell us roughly what you send and to how many recipients. There is no volume commitment and no separate product.
  • 02Reverse DNS on both v4 and v6 is self-service from the console and propagates in minutes.
  • 03Addresses are reputation-checked before allocation. If yours turns out to be listed somewhere, support swaps it at no charge.
  • 04Outbound volume is rate-limited on new instances for the first week, then lifted automatically.

What you have to do

SPF, DKIM and DMARC, correctly, before you send anything. A working v6 PTR, which is the step most guides skip and the one large providers check. And a real abuse contact on the domain, because the alternative to answering complaints is having them answered for you.